This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section
A communication system can be seen as a facility that enables communication sessions between two or more entities such as user equipment and/or other nodes associated with the communication system. The communication may comprise, for example, communication of voice, data, multimedia and so on. A session may, for example, be a telephone call between users or multi-way conference session, or a communication session between user equipment and an application server (AS), for example a service provider server. The establishment of these sessions generally enables a user to be provided with various services.
A communication system typically operates in accordance with a given standard or specification which sets out what the various entities associated with the communication system are permitted to do and how that should be achieved. For example, the standard or specification may define if the user, or more precisely, user equipment is provided with a circuit switched service and/or a packet switched service. Communication protocols and/or parameters which shall be used for the connection may also be defined. In other words, a specific set of “rules” on which the communication can be based on needs to be defined to enable communication by means of the system.
Communication systems providing wireless communication for user equipment are known. An example of the wireless systems is the public land mobile network (PLMN) and another example is the wireless local area network (WLAN). Fixed broadband access is another type of access.
The term “service” used above and hereinafter will be understood to broadly cover any service or goods which a user may desire, require or be provided with. The term also will be understood to cover the provision of complimentary services. In particular, but not exclusively, the term “service” will be understood to include Internet protocol multimedia IM services, conferencing, telephony, gaming, rich calls, etc.
An example of the services that may be offered for users such as the subscribers to a communication system are the so called multimedia services. Some of the communication systems enabled to offer multimedia services are known as Internet Protocol (IP) Multimedia networks. IP Multimedia (IM) functionalities can be provided by means of an IP Multimedia Core Network (CN) subsystem, or briefly IP Multimedia subsystem (IMS). The IMS includes various network entities for the provision of the multimedia services. The IMS services are intended to offer, among other services, IP connections between mobile user equipment.
Peer-to-peer (P2P) overlay networks, hereafter referred to as peer-to-peer networks or P2P networks, operating over conventional IP networks share a common characteristic, i.e., the full distribution of the resources with minimum intervention of centralized servers assisting the peers to share resource material. P2P networks are typically comprised of a group of elements (typically personal computers), known as peers, connected via a packet switched network such as the Internet. Resources, which can be anything, typically a file (such as an image, video clip or soundtrack) or a data stream (such as a video stream or digitally encoded voice data), are stored or generated in the peer elements. A P2P network therefore typically differs from a conventional resource network in that the conventional network uses a centralized server to typically provide the resource, whereas in the P2P network, the participants in the network provide the resource to other users. Known P2P networks such as Kazaa, WinMX, Emule, BitTorrent are file-sharing networks, whereas Skype is a telephony P2P network.
Although P2P networks are known for conventional PC networks, the use of P2P networks over wireless communication links has several problems.
A first problem with the use of P2P networks over a wireless communications network is that unlike a conventional user using a broadband connection the user is not continuously connected to the network. User equipment can temporarily be moved into locations where wireless coverage does not exist, for example underground in railway or road tunnels. Thus, IP users connecting via a general packet radio system (GPRS) communications system or via a wireless local area network (WLAN) connection where connections are not permanent would generate a significant amount of signalling overhead for the whole network as the users come in and out of the P2P network.
A second problem is that user equipment connected over a wireless communications network is typically network address translated. In other words the GPRS or WLAN network server provides the node with a private Internet protocol (IP) address. This private IP is not directly reachable from the internet and traffic has to be directed to a public IP address of the address translator which then redirects the packet to the user equipment. This limits the availability of the user equipment at the time of joining the P2P network. For example if the user equipment moves from one GPRS or WLAN network to a different network then the user equipment will receive a different private IP address and a different public IP address requiring the P2P network to be informed of the changes and increasing the signalling overhead.
WO2005/41534 discloses a pure ad-hoc network which has the disadvantages as described above.
US2003/125063 discloses a wireless communication P2P network where a series of network servers mirrors the content on the user equipment. Such systems are inefficient in that in order for the system to operate correctly, the mirrored content must initially be uploaded from the user equipment and maintained so that the content is maintained to be the same as that currently stored on the user equipment. This system is therefore both bandwidth inefficient, as all data is required to be uploaded to the mirror, and resource inefficient, as the same resource exists in at least two different locations.
US2004/0243665 and US2004/0243580 disclose a mobile user system for allowing communication between node users for peer-to-peer services.
Matuszewski, M., Beijar, N., Lehtinen, J. and Hyyryläinen, T. (2006) “Mobile Peer-to-Peer Content Sharing Application,” Proceedings of IEEE Consumer Communications and Networking Conference, January, contains a demonstration of the P2P content sharing service, however such a system is modelled using a single super-peer node and does not provide information of the signalling associated with the system.
Beijar, N., Matuszewski, M., Lehtinen, J., and Hyyryläinen, T. (2005) “Mobile Peer-to-Peer Content Sharing Services in IMS,” Proceedings of The International Conference on Telecommunication Systems, Modeling and Analysis 2005, November also contains a P2P content sharing architecture which could be applied to a IMS network. However it does not specifically disclose how to implement a P2P network with IMS signalling over the IMS architecture.